FXS C/D HRS dosing pump series has two different operating modes: traditional mode and HRS advanced modes. High Rating System is a patented concept that allows working range pump widening. By setting working pressure (within a preset range of values) the pump automatically self-controls the flow rate at operator's desired working values. Flow rate can then be set within 0,1l/h step value. Compared to ordinary pumps HRS High Rating System allows an improved pump performance and an enlarged operating range, making possible the correct flow rate setting at different pressures avoiding volume fluctuations connected to different working pressures, even with high viscous liquids.